1. Field of the Invention
The present invention relates to a radio access system supporting multi-radio access technology (RAT) and, more particularly, to a method and apparatus for transmitting and receiving data over two or more heterogeneous networks.
2. Related Art
In a conventional radio communication environment supporting two or more heterogeneous networks, although a terminal has capabilities to access multi-RAT, the terminal is unable to access the multi-RAT at the same time and transmit and receive data to and from the two or more heterogeneous networks at the same time.
That is, a conventional terminal supporting multi-RAT accesses any one RAT based on switching and transmits and receives data over one network. Accordingly, if a terminal having multi-RAT capabilities transmits and receives data over a specific network and transmits and receives data over a network different from the specific network, the transmission and reception of data over any one network is stopped.
Accordingly, in the prior art, a terminal having capabilities supporting two or more heterogeneous networks is able to perform communication by using different networks, but efficiency is limited because the terminal operates based on simple switching.
Furthermore, since different networks independently operate, an inefficient operation is performed from a viewpoint of the overall flow management of a terminal.
Accordingly, a method of a mobile station (MS), having a multi-RAT capability, transmitting and receiving data at the same time over 2 or more networks has been defined. However, overall contents of a multi-RAT capability negotiation process procedure have been defined, but detailed solutions to detailed contents and method of each operation have not been proposed.
In particular, it is clear that a multi-RAT MS must perform a scanning procedure on a secondary system in order to transmit and receive data to and from heterogeneous networks, that is, a primary system and the secondary system at the same time, but there is no detailed solution regarding that the a multi-RAT MS has to perform scanning on the secondary system through what method.
Furthermore, the number of APs belonging to the coverage of a cellular network is gradually increased, and that an MS scans all neighbor APs can be inefficient in terms of power efficiency.